Modelling the luminosities and sizes of radio galaxies: radio luminosity function at z = 6

Abstract

We present a model to predict the luminosity function for radio galaxies and their linear size distribution at any redshift. The model takes a black hole mass function and Eddington ratio distribution as input and tracks the evolution of radio sources, taking into account synchrotron, adiabatic and inverse Compton energy losses. We first test the model at z = 2 where plenty of radio data is available and show that the radio luminosity function (RLF) is consistent with observations. We are able to reproduce the break in luminosity function that separates locally the FRI and FRII radio sources. Our prediction for linear size distribution at z = 2 matches the observed distribution too. We then use our model to predict a RLF and linear size distribution at z = 6, as this is the epoch when radio galaxies can be used as probes of reionisation. We demonstrate that higher inverse Compton losses lead to shorter source lifetimes and smaller sizes at high redshifts. The predicted sizes are consistent with the generally observed trend with redshift. We evolve the z = 2 RLF based on observed quasar space densities at high redshifts, and show that our RLF prediction at z = 6 is consistent. Finally, we predict the detection of 0.63, 0.092 and 0.0025 z>=6 sources per sq. degree at flux density limits of 0.1, 0.5 and 3.5 mJy. We assess the trade-off between coverage area and depth and show that LOFAR surveys with flux density limits of 0.1 and 0.5 mJy would are the most efficient at detecting a large number of z>=6 radio sources.

13 pages, 11 figures, Accepted for publication in MNRAS

References in corpus (16)

• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• Distant Radio Galaxies and their Environments
• The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7
• Protoclusters associated with z > 2 radio galaxies. I. Characteristics of high redshift protoclusters
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• Black-Hole Spin and Galactic Morphology
• Luminosity function, sizes and FR dichotomy of radio-loud AGN
• Constraining the radio-loud fraction of quasars at z>5.5
• High redshift quasars in the COSMOS survey: the space density of z>3 X-ray selected QSOs
• The Luminosity Function of high-redshift QSOs - A combined analysis of GOODS and SDSS
• The triggering probability of radio-loud AGN: A comparison of high and low excitation radio galaxies in hosts of different colors
• The Lifetime of FRIIs in Groups and Clusters: Implications for Radio-Mode Feedback
• Radio-AGN Feedback: When the Little Ones were Monsters
• Bounds on Black Hole Spins
• 21cm Forest with the SKA

Cited by in corpus (5)

• AGN and their host galaxies in the local Universe: two mass independent Eddington ratio distribution functions characterize black hole growth
• A search for faint high-redshift radio galaxy candidates at 150 MHz
• The detectability of strong 21 centimetre forest absorbers from the diffuse intergalactic medium in late reionisation models
• Statistical Detection of IGM Structures during Cosmic Reionization using Absorption of the Redshifted 21 cm line by HI against Compact Background Radio Sources
• LOFAR properties of SILVERRUSH Ly$\alpha$ emitter candidates in the ELAIS-N1 field